Adds fopen() and fexist() and tests for all existing functions

src/file.asm

@@ -54,7 +54,7 @@ section .text
 
 ;----- fopen(*file[], char mode) -----;
 ; Opens a file
-; Return value: Pointer to opened file pointer, 0 (EOS) otherwise.
+; Return value: Pointer to opened file pointer, -errno otherwise
 ; Possible modes:
 ;	'r'	Read-only, file must exist
 ;	'w'	Write-only. Creates empty file or truncates an existing file
@@ -68,6 +68,82 @@ section .text
 ;	rdi	(arg) Pointer to string holding (path+)file name
 ;	rsi	Mode to open the file with (see description above)
 fopen:
+	%macro createFile 1
+	push	rdi
+	push	rsi
+	call	fexist
+	pop	rsi
+	pop	rdi
+	mov	rax, 1
+	jz	%%createFile
+	jmp	%1
+	%%createFile:
+	push	rsi
+	push	rdi
+	call	umask_get
+	pop	rdi
+	push	rdi
+	not	rax
+	mov	rsi, 00666q
+	and	rsi, rax
+	mov	rax, NR_creat
+	syscall
+	pop	rdi
+	pop	rsi
+	%endmacro
+	;;;
+	;;; ENTRY
+	;;;
+	sub	rsp, SIZE_QWORD
+
+	cmp	sil, 'r'
+	je	.setMode_r
+	cmp	sil, 'w'
+	je	.setMode_w
+	cmp	sil, 'a'
+	je	.setMode_a
+	cmp	sil, 'R'
+	je	.setMode_R
+	cmp	sil, 'W'
+	je	.setMode_W
+	cmp	sil, 'A'
+	je	.setMode_A
+	mov	rax, -EINVAL
+	jmp	.quit
+
+	.setMode_r:
+	mov	rsi, O_RDONLY
+	jmp	.open
+	.setMode_w:
+		createFile .open_w
+	.open_w:
+	mov	rsi, O_WRONLY | O_TRUNC
+	jmp	.open
+	.setMode_a:
+		createFile .open_a
+	.open_a:
+	mov	rsi, O_WRONLY | O_APPEND
+	jmp	.open
+	.setMode_R:
+	mov	rsi, O_RDWR
+	jmp	.open
+	.setMode_W:
+		createFile .open_W
+	.open_W:
+	mov	rsi, O_RDWR | O_TRUNC
+	jmp	.open
+	.setMode_A:
+		createFile .open_A
+	.open_A:
+	mov	rsi, O_RDWR | O_APPEND
+	jmp	.open
+
+	.open:
+	mov	rax, NR_open
+	syscall
+
+	.quit:
+	add	rsp, SIZE_QWORD
 	ret
 
 ;----- fclose(file) -----;
@@ -96,4 +172,15 @@ fclose:
 ;	rax*	(ret)
 ;	rdi	(arg) Pointer to string holding (path+)file name
 fexist:
+	mov	rsi, 'r'
+	call	fopen
+	test	rax, rax
+	js	.not_exist
+	mov	rdi, rax
+	call	fclose
+	mov	rax, 1
+	jmp	.quit
+	.not_exist:
+	xor	rax, rax
+	.quit:
 	ret